OpenGL - lighting of vertices outside clip range
- by hmp
I have a problem with lighting in my OpenGL application. When one of the vertices of a drawn polygon goes outside the front clip plane (or has z<0, I'm not sure which), the polygon stops being lighted properly.
This however happens on only one machine I tested, with Intel GMA950 card. On nVidia and ATI cards everything looks fine.
I guess I am breaking some OpenGL rule here? How should I deal with it?
I'd try dividing the scene into smaller polygons, but I'm not sure if it guarantees the case is eliminated (all polygons stepping outside the clipping range are offscreen).